1.列出当前系统上所有已经登录的用户的用户名，注意：同一个用户登录多次，则只显示一次即可
[root@tom ~]# who | cut -d ' ' -f1 | sort -uroot
2.取出当前系统上被用户当作其默认shell的最多的那个shell
[root@tom ~]# cat /etc/passwd | cut -d ':' -f7 | uniq -c | sort -nr | head -1 22 /sbin/nologin
3.将/etc/passwd中的第三个字段数值最大的后10个用户的信息全部改为大写后保存至/tmp/maxusers.txt文件中
[root@tom ~]# cat /etc/passwd | sort -n -t ':' -k3 |tail | tr 'a-z' 'A-Z' >/tmp/maxusers.txt
[root@tom ~]# cat /tmp/maxusers.txt AVAHI-AUTOIPD:X:170:170:AVAHI IPV4LL STACK:/VAR/LIB/AVAHI-AUTOIPD:/SBIN/NOLOGINABRT:X:173:173::/ETC/ABRT:/SBIN/NOLOGINOPENERP:X:494:501::/OPT/OPENERP/:/BIN/BASHUNBOUND:X:495:491:UNBOUND DNS RESOLVER:/ETC/UNBOUND:/SBIN/NOLOGINVBOXADD:X:496:1::/VAR/RUN/VBOXADD:/BIN/FALSEPULSE:X:497:495:PULSEAUDIO SYSTEM DAEMON:/VAR/RUN/PULSE:/SBIN/NOLOGINSASLAUTH:X:498:76:"SASLAUTHD USER":/VAR/EMPTY/SASLAUTH:/SBIN/NOLOGINRTKIT:X:499:496:REALTIMEKIT:/PROC:/SBIN/NOLOGINSAM:X:500:500:SAMUEL:/HOME/SAM:/BIN/BASHNFSNOBODY:X:65534:65534:ANONYMOUS NFS USER:/VAR/LIB/NFS:/SBIN/NOLOGIN
4.取出当前主机的IP地址，提示：对ifconfig命令的结果进行切分
[root@tom ~]# ifconfig|grep 'inet[[:space:]].*' | cut -d ':' -f2 | cut -d ' ' -f1 172.18.11.121127.0.0.1
5.显示/var目录下一级子目录或文件的总个数
[root@tom ~]# tree -L 1 /var | tail -n 122 directories, 0 files
6.取出/etc/group文件中第三个字段数值最小的10个组的名字
[root@tom ~]# cat /etc/group | sort -n -t ':' -k3 | head | cut -d ':' -f1rootbindaemonsysadmttydisklpmemkmem
7.将/etc/fstab和/etc/issue文件的内容合并为同一个内容后保存至/tmp/etc.test文件中
[root@tom ~]# cat /etc/fstab /etc/issue > /tmp/etc.test[root@tom ~]# cat /tmp/etc.test## /etc/fstab# Created by anaconda on Sun Nov 6 13:58:01 2016## Accessible filesystems, by reference, are maintained under '/dev/disk'# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info#UUID=4426c2ca-c804-4bd9-b071-9e7c83e12625 / ext4 defaults 1 1UUID=77540bb8-0514-478c-8b63-ca165ab1d6a4 /boot ext4 defaults 1 2UUID=300c1246-2d1f-4a8f-880e-b75556d52037 /home ext4 defaults 1 2UUID=274f62f3-a54f-4d36-b9ec-25ebfce2af16 /opt ext4 defaults 1 2UUID=82a0e328-a2f5-4e9a-8d4b-44b1f0b9e06c swap swap defaults 0 0tmpfs /dev/shm tmpfs defaults 0 0devpts /dev/pts devpts gid=5,mode=620 0 0sysfs /sys sysfs defaults 0 0proc /proc proc defaults 0 0CentOS release 6.8 (Final)Kernel \r on an \m
8.请总结描述用户和组管理类命令的使用方法并完成以下练习：
创建用户命令：useradd 其用法：useradd [option] username
option：
-u：设定用户UID
-g：指定用户所属基本组
-c：添加用户详细信息
-d：设定用户主目录
-s：设定用户默认shell
删除用户命令：userdel 其用法：userdel [option] username
option：
-r：在删除用户时，删除用户主目录
用户添加密码：passwd 其用法：passwd [option] username
option：
-l：锁定用户
-u：解锁用户
用户属性修改：usermod 其用法：usermod [option] username
option：
-u：用户更换新UID
-g：用户更换新GID
-G：设定新的主目录，如果需要移动用户文件，需用同时使用-m选项
-l：设定新的用户名
-L：锁定用户
-U：解锁用户
创建组命令：groupadd 其用法：groupadd [option] groupname
option：
-g：指定组GID
-r：创建系统组
删除组命令：groupdel 其用法：groupdel groupname
组密码添加：gpasswd 其用法：gpasswd [option] group
option：
-a：添加指定用户至指定组
-d：从指定组中删除指定用户
-A：设定有管理员权限的用户
(1)、创建组distro，其GID为2016；
[root@tom ~]# groupadd -g 2016 distro[root@tom ~]# cat /etc/group | grep distrodistro:x:2016:
(2)、创建用户mandriva, 其ID号为1005；基本组为distro；
[root@tom ~]# useradd -u 1005 -g distro mandriva[root@tom ~]# id mandrivauid=1005(mandriva) gid=2016(distro) groups=2016(distro)
(3)、创建用户mageia，其ID号为1100，家目录为/home/linux;
[root@tom ~]# useradd -u 1100 -d /home/linux mageia[root@tom ~]# cat /etc/passwd | grep mageiamageia:x:1100:1100::/home/linux:/bin/bash
(4)、给用户mageia添加密码，密码为mageedu；
[root@tom ~]# passwd mageia[root@tom ~]# cat /etc/shadow | grep mageiamageia:$6$R82Ll/CQ$gzuzsUbmoTtFhzwYb3WLb8pJ84gYrrqgCMQ8XKDrLoo0oLgBUhYo9VycKZGpg7oJi2YKgopXB9ioKbuQuzMRU.:17160:0:99999:7:::
(5)、删除mandriva，但保留其家目录；
[root@tom ~]# userdel mandriva[root@tom ~]# id mandrivaid: mandriva: No such user[root@tom ~]# ls -l /home/total 28drwx------. 4 mageia mageia 4096 Dec 25 11:44 linuxdrwx------. 2 root root 16384 Nov 6 13:56 lost+founddrwx------. 4 1005 distro 4096 Dec 25 11:41 mandrivadrwx------. 29 sam sam 4096 Dec 16 16:35 sam
(6)、创建用户slackware，其ID号为2002，基本组为distro，附加组peguin；
[root@tom ~]# useradd -u 2002 -g distro -Gpeguin slackware[root@tom ~]# id slackwareuid=2002(slackware) gid=2016(distro) groups=2016(distro),2017(peguin)
(7)、修改slackware的默认shell为/bin/tcsh；
[root@tom ~]# usermod -s /bin/tcsh slackware[root@tom ~]# cat /etc/passwd | grep slackwareslackware:x:2002:2016::/home/slackware:/bin/tcsh
(8)、为用户slackware新增附加组admins；
[root@tom ~]# gpasswd -a slackware adminsAdding user slackware to group admins[root@tom ~]# id slackwareuid=2002(slackware) gid=2016(distro) groups=2016(distro),2017(peguin),2018(admins)
(9)、为slackware添加密码，且要求密码最短使用期限为3天，最长为180天，警告为3天；
[root@tom ~]# passwd -n 3 -x 180 -w 3 slackware[root@tom ~]# passwd slackware[root@tom ~]# cat /etc/shadow | grep slackwareslackware:$6$GQZ4Tacc$tgBjVYIKAQUmg1l2VIimrEwEVn5fTOEBlO3XLsBjk4H0PAcaLwG0andgr9FwWRMN9pJmOjJ559vYoRYDj3voo0:17160:3:180:3:::
(10)、添加用户openstack，其ID号为3003, 基本组为clouds，附加组为peguin和nova；
[root@tom ~]# useradd -u 3003 -g clouds -G peguin,nova openstack[root@tom ~]# id openstackuid=3003(openstack) gid=2020(clouds) groups=2020(clouds),2017(peguin),2019(nova)
(11)、添加系统用户mysql，要求其shell为/sbin/nologin；
[root@tom ~]# useradd -rs /sbin/nologin mysql[root@tom ~]# cat /etc/passwd | grep mysqlmysql:x:493:490::/home/mysql:/sbin/nologin
(12)、使用echo命令，非交互式为openstack添加密码。
[root@tom ~]# echo "mageedu" | passwd --stdin openstackChanging password for user openstack.passwd: all authentication tokens updated successfully.[root@tom ~]# cat /etc/shadow | grep openstackopenstack:$6$cLZAIEmy$DgbAhNEK9PFNYFcEX5BAZlnSiH7dfrhBZQiXiLA7N/KGMdyWTEBbVqBoAf/uZu3xS//KnOXnqUF5ANlYwpGOf/:17160:0:99999:7:::
9.复制/etc/skel目录为/home/tuser1，要求/home/tuser1及其内部文件的属组和其它用户均没有任何访问权限
[root@tom ~]# cp -ar /etc/skel /home/tuser1[root@tom ~]# chmod -R 600 /home/tuser1[root@tom ~]# ll -a /home/tuser1total 28drw-------. 4 root root 4096 Nov 6 16:06 .drwxr-xr-x. 9 root root 4096 Dec 25 12:58 ..-rw-------. 1 root root 18 May 11 2016 .bash_logout-rw-------. 1 root root 176 May 11 2016 .bash_profile-rw-------. 1 root root 124 May 11 2016 .bashrcdrw-------. 2 root root 4096 Nov 12 2010 .gnome2drw-------. 4 root root 4096 Nov 6 13:58 .mozilla
[root@tom ~]# ll -a /hometotal 48drwxr-xr-x. 9 root root 4096 Dec 25 12:58 .dr-xr-xr-x. 25 root root 4096 Dec 25 09:35 ..drwx------. 4 mageia mageia 4096 Dec 25 11:44 linuxdrwx------. 2 root root 16384 Nov 6 13:56 lost+founddrwx------. 4 1005 distro 4096 Dec 25 11:41 mandrivadrwx------. 4 openstack clouds 4096 Dec 25 12:06 openstackdrwx------. 29 sam sam 4096 Dec 16 16:35 samdrwx------. 4 slackware distro 4096 Dec 25 11:52 slackwaredrw-------. 4 root root 4096 Nov 6 16:06 tuser1
10.显示/proc/meminfo文件中以大写或小写S开头的行
[root@tom ~]# grep '^[sS].*' /proc/meminfo SwapCached: 0 kBSwapTotal: 4094972 kBSwapFree: 4094972 kBShmem: 220 kBSlab: 110528 kBSReclaimable: 51020 kBSUnreclaim: 59508 kB
[root@tom ~]# grep '\b[sS].*' /proc/meminfo SwapCached: 0 kBSwapTotal: 4094972 kBSwapFree: 4094972 kBShmem: 220 kBSlab: 110552 kBSReclaimable: 51020 kBSUnreclaim: 59532 kB
11.显示/etc/passwd文件中其默认shell为非/sbin/nologin的用户
[root@tom ~]# cat /etc/passwd | grep '.*[^/sbin/nologin]$'root:x:0:0:root:/root:/bin/bashsync:x:5:0:sync:/sbin:/bin/synchalt:x:7:0:halt:/sbin:/sbin/haltsam:x:500:500:samuel:/home/sam:/bin/bashvboxadd:x:496:1::/var/run/vboxadd:/bin/falseopenerp:x:494:501::/opt/openerp/:/bin/bashpostgres:x:26:26:PostgreSQL Server:/var/lib/pgsql:/bin/bashmageia:x:1100:1100::/home/linux:/bin/bashslackware:x:2002:2016::/home/slackware:/bin/tcshopenstack:x:3003:2020::/home/openstack:/bin/bash
12.显示/etc/passwd文件中其默认shell为/bin/bash的用户
[root@tom ~]# cat /etc/passwd | grep '.*bash$'root:x:0:0:root:/root:/bin/bashsam:x:500:500:samuel:/home/sam:/bin/bashopenerp:x:494:501::/opt/openerp/:/bin/bashpostgres:x:26:26:PostgreSQL Server:/var/lib/pgsql:/bin/bashmageia:x:1100:1100::/home/linux:/bin/bashopenstack:x:3003:2020::/home/openstack:/bin/bash
13.找出/etc/passwd文件中的一位数或两位数
[root@tom ~]# grep '\b[0-9]\{1,2\}\b' /etc/passwdroot:x:0:0:root:/root:/bin/bashbin:x:1:1:bin:/bin:/sbin/nologindaemon:x:2:2:daemon:/sbin:/sbin/nologinadm:x:3:4:adm:/var/adm:/sbin/nologinlp:x:4:7:lp:/var/spool/lpd:/sbin/nologinsync:x:5:0:sync:/sbin:/bin/syncshutdown:x:6:0:shutdown:/sbin:/sbin/shutdownhalt:x:7:0:halt:/sbin:/sbin/haltmail:x:8:12:mail:/var/spool/mail:/sbin/nologinuucp:x:10:14:uucp:/var/spool/uucp:/sbin/nologinoperator:x:11:0:operator:/root:/sbin/nologingames:x:12:100:games:/usr/games:/sbin/nologingopher:x:13:30:gopher:/var/gopher:/sbin/nologinftp:x:14:50:FTP User:/var/ftp:/sbin/nologinnobody:x:99:99:Nobody:/:/sbin/nologindbus:x:81:81:System message bus:/:/sbin/nologinvcsa:x:69:69:virtual console memory owner:/dev:/sbin/nologinrpc:x:32:32:Rpcbind Daemon:/var/cache/rpcbind:/sbin/nologinrpcuser:x:29:29:RPC Service User:/var/lib/nfs:/sbin/nologinhaldaemon:x:68:68:HAL daemon:/:/sbin/nologingdm:x:42:42::/var/lib/gdm:/sbin/nologinntp:x:38:38::/etc/ntp:/sbin/nologinapache:x:48:48:Apache:/var/www:/sbin/nologinsaslauth:x:498:76:"Saslauthd user":/var/empty/saslauth:/sbin/nologinpostfix:x:89:89::/var/spool/postfix:/sbin/nologinsshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologintcpdump:x:72:72::/:/sbin/nologinoprofile:x:16:16:Special user account to be used by OProfile:/home/oprofile:/sbin/nologinvboxadd:x:496:1::/var/run/vboxadd:/bin/falsepostgres:x:26:26:PostgreSQL Server:/var/lib/pgsql:/bin/bash 14.显示/etc/rc.d/rc.sysinit文件中以#开头，后面跟至少一个空白字符，而后又有至少一个非空白字符的行
[root@tom ~]# grep '^#[[:space:]][^[:space:]].*' /etc/rc.d/rc.sysinit # /etc/rc.d/rc.sysinit - run once at boot time# Taken in part from Miquel van Smoorenburg's bcheckrc.# Check SELinux status# Print a text banner.# Only read this once.# Initialize hardware# Set default affinity# Load other user-defined modules# Load modules (for backward compatibility with VARs)# Configure kernel parameters# Set the hostname.# Sync waiting for storage.# Device mapper & related initialization# Start any MD RAID arrays that haven't been started yet# Remount the root filesystem read-write.# Clean up SELinux labels# If relabeling, relabel mount points.# Mount all other filesystems (except for NFS and /proc, which is already# mounted). Contrary to standard usage,# filesystems are NOT unmounted in single user mode.# The 'no' applies to all listed filesystem types. See mount(8).# Check to see if a full relabel is needed# Update quotas if necessary# Initialize pseudo-random number generator# Configure machine if necessary.# Clean out /.# Do we need (w|u)tmpx files? We don't set them up, but the sysadmin might...# Clean up /var.# Clean up utmp/wtmp# Clean up various /tmp bits# Make ICE directory# Start up swapping.# Set up binfmt_misc# Boot time profiles. Yes, this should be somewhere else.# Now that we have all of our basic modules loaded and the kernel going,# let's dump the syslog ring somewhere so we can find it later# create the crash indicator flag to warn on crashes, offer fsck with timeout# Let rhgb know that we're leaving rc.sysinit
15.打出netstat -tan命令执行结果中以‘LISTEN’，后或跟空白字符结尾的行
[root@tom ~]# netstat -tan | grep '.*LISTEN\b'tcp 0 0 0.0.0.0:36015 0.0.0.0:* LISTEN tcp 0 0 0.0.0.0:111 0.0.0.0:* LISTEN tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN tcp 0 0 127.0.0.1:631 0.0.0.0:* LISTEN tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN tcp 0 0 :::59501 :::* LISTEN tcp 0 0 :::111 :::* LISTEN tcp 0 0 ::1:631 :::* LISTEN tcp 0 0 ::1:25 :::* LISTEN
16.添加用户bash, testbash, basher, nologin (此一个用户的shell为/sbin/nologin)，而后找出当前系统上其用户名和默认shell相同的用户的信息
[root@tom ~]#useradd bash[root@tom ~]#useradd testbash[root@tom ~]#useradd basher[root@tom ~]#useradd nologin[root@tom ~]# tail -n 4 /etc/passwdbash:x:3004:3004::/home/bash:/bin/bashtestbash:x:3005:3005::/home/testbash:/bin/bashbasher:x:3006:3006::/home/basher:/bin/bashnologin:x:3007:3007::/home/nologin:/sbin/nologin
[root@tom ~]# grep "^\([[:alnum:]]\{1,\}\):.*\1$" /etc/passwdsync:x:5:0:sync:/sbin:/bin/syncshutdown:x:6:0:shutdown:/sbin:/sbin/shutdownhalt:x:7:0:halt:/sbin:/sbin/haltbash:x:3004:3004::/home/bash:/bin/bashnologin:x:3007:3007::/home/nologin:/sbin/nologin